1. Field of the Invention
The present invention relates to a crash acceleration pulse control block for a vehicle. More particularly, the present invention relates to a crash acceleration pulse control block confirmed to provide reliable initial crash acceleration data even in situations where the engine specification or the vehicle weight have been changed to thereby more accurately deploy an airbag.
2. Description of the Related Art
In general, an airbag unit operates when a vehicle accident occurs in order to deploy an airbag according to the crash detected by the airbag unit. In other words, when it is expected that a vehicle occupant may be injured due to predicted crash parameters, the airbag unit deploys the airbag so as to reduce impact applied to the occupant through the impact absorbing performance of the airbag.
For example, when a vehicle collides with a wall, as shown in FIG. 6, an ACU (airbag control unit) detects the crash pulse. Acceleration of the vehicle detected by the ACU is converted into velocity and vibration energy as shown in FIGS. 7 and 8 through a digital data process, such as filtering.
If the velocity and vibration energy increase beyond a critical line, the ACU deploys the airbag. However, if the vehicle crash occurs with low acceleration, as represented in FIG. 6 with a dotted line, relatively low velocity and vibration energy data are detained. These low valves are potentially below the critical line as shown in FIGS. 7 and 8 (dashed line), so the ACU may not deploy the airbag.
The level of the vehicle crash is determined according to the level of acceleration detected by means of an accelerometer of the ACU installed in the vehicle. In addition, the airbag is deployed depending on the level of acceleration detected by means of an accelerometer.
Generally, if the vehicle collides with a rigid wall, crash impact is applied over the relatively large area of the vehicle so that the vehicle is directly influenced by the vehicle crash. In this case, the level of acceleration caused by the vehicle crash is prominently represented so that the ACU can easily determine the deployment of the airbag. However, when a frontal crash, an offset crash, a side impact crash or a rear-end crash, for example, occurs between vehicles, the level of acceleration may be determined depending on rigidity and the contact area between vehicles, so relatively low initial acceleration may be represented in general. This means that the vehicles have low rigidity and the contact area between the vehicles is small, so that the vehicles subject to such a crash represent the level of acceleration significantly lower than that of the vehicles colliding with the rigid wall under the same crash velocity condition. If the level of initial acceleration of the vehicle is small, the ACU may not deploy the airbag, causing damage to the occupants.
Another problem of the prior art is derived from mass production of the vehicles. That is, since various kinds of engines and optional components are installed in the vehicles having the same chassis, vehicles may be equipped with engines and optional components having the different weight. For this reason, acceleration variation may occur in a range of about 10% even if the crash test is performed using vehicles having the same vehicle class under the same crash velocity. Thus, it is difficult for the ACU to determine the deployment of the airbag.
Alternatively, in order to allow vehicles having different specifications and using the same chassis to represent similar initial crash acceleration under the same crash condition, there has been suggested a method of providing the vehicles with bumpers having different sizes or shapes, respectively. However, this method has no practical use because the cost of the bumper is very expensive.